A final explanation is that he ran for president on two contradictory platforms: as a reformer who would clean up the system, and as a unity candidate who would transcend the lines of red and blue. He has pursued the one with which he is most comfortable given the constraints of his character, consistently choosing the message of bipartisanship over the message of confrontation.
But the arc of history does not bend toward justice through capitulation cast as compromise. It does not bend when 400 people control more of the wealth than 150 million of their fellow Americans. It does not bend when the average middle-class family has seen its income stagnate over the last 30 years while the richest 1 percent has seen its income rise astronomically. It does not bend when we cut the fixed incomes of our parents and grandparents so hedge fund managers can keep their 15 percent tax rates. It does not bend when only one side in negotiations between workers and their bosses is allowed representation. And it does not bend when, as political scientists have shown, it is not public opinion but the opinions of the wealthy that predict the votes of the Senate. The arc of history can bend only so far before it breaks.